Temperature regulation system for electric discharge devices



Sept. 14, 1951-3. v 1- BQURNE 2,329,584

TEMPERATURE REGULATION SYSTEM FOR ELECTRIC DISCHARGE DEVICES Filed Jan. 27, 1941 Fig. 1.

A l A l l l A l u TO LAMP) TERMINALS fifl lnventofz Harv Kebbett Bourne,

His A=t=torne9.

Patented Sept. 14, 1943 TEMPERATURE REGULATION amm ELECTRIC DISCHARGE DEVICES Harry Kebbell Bourne, Rugby, England assignor to General Electric g NewYork v a Company. a corporation of 'ApplicationJanuary 27, 194 1, SerialNo. 376,242

, r In Great Britain February 17, 195A) ill-Claims. (c1. zen-2 7.5) a

My invention relates to thetemp rature regulation of electric discharge devices and more particularly to the temperature regulation of discharge lamps of the: highrpressure metal vapor type. V.

The current carrying capacity of. an electric discharge lamp of the high pressure metal vapor type is limited by the.v operating temperature of the lamp envelope." Ifthe temperature is too high it will cause deterioration of the refractory material of the bulb. If, howevenxthe lamp is cooled by means of a blast of air or. other cooling medium the temperature is lowered and consequently the capacity may be increased very considerably. -It'is possible by this means to make such lamps operate .at very high wattages without a large increase in the size of the bulb.

The reduction in bulb volume "not -only decreases the cost of the lamp but also the danger 'of explosion. At the J higher wattages the luminous efiiciency and thelin'trinsic" brilliancy or intensity of the light source arealso increased. Because of the greater light output and decreased size these sources 'become'suitable for various projection applications.

However, 'in lamps as previously operated, that is in free air orwith a simple cooling blast, the long-delays before useful light output is obtained is a serious disadvantage -for projection purposes. lThese delays resulted from: (1) the time taken forthelamp to reach its correct operating pressure and temperature after'having been switched (min the cold state; and (2) a the time taken for 'thelarnpto cool down to allow restriking of the arc discharge if the lamp is extinguished for any reason. as a power failure,and'isswitched onwhen still hot. N

It'is an object of my invention to minimize these disadvantages-by providing means whereby these times are very considerably reduced thereby to extend the field of application of the lamps. Further objects and advantages of my invention will appear from the following detailed description and drawings; l

According to the invention I provide auxiliary heating means, an auxiliary directive cooling means and an auxiliary starting device. These and the main cooling means are operated in a predetermined sequence. A further cooling means may be employed, the function of which is to cool the'seals. Bythis. means very large the cold lamp with the auxiliary heater switched lows: On switching on fi'om'cold'it is necessary to reachthe desired operating temperature as quickly as possible. This is done by running on and the cooling airturned oil. When the lamp has reached a certain temperature, the

heater is switched off and thecoolingblast isturned on and the lampwill then continue to run up to its normal operating temperature corresponding to its normal operatingwattag'e determined by the-value of the impedance connected in series withthe lamp. In the event,

of a failure-of the mains supply followed by a restoration of the supply. a directive cooling means comes into-operation, and this causes the mercury tocondense rapidly; at a point on the lamp bulbr-at which it can receive heat rapid.-

- ly'from the heater. The pressure'inv the lamp currents may be carried through the seals wherebylamps of very'high 'wattagemay be made more easily. i Theuc orrect':sequence:Iotloperating is as folfalls rapidly; andwhen it is sufilciently-low the lamp will restrike whereupon the cooling means arefturned-ofiand the'heater is again switched on. The lamp then runsup rapidly to the value of the wattageat which the heater is switched off and the cooling blast is turned on.

The invention; will now be described by reference tothe accompanying drawing in which corresponding numerals indicate corresponding elements throughout. and inwhich Fig.1 is a diagrammaticrepresentation of the'heating and cooling; meansofthe present invention; Fig. 2

represents a circuit for operating said means;

and Fig. 3 a modified form of the: lamp of Fig.- 1., In Fig.1 of the drawing a high pressure mercury vapor projection lamp l is mounted in such to condense the-mercury rapidly'when it is required to restrike the arc in the hot lamp. A Tesla coil, 6 is connected to an auxiliary electrode in the lamp in order to reduce stillfurtherthe striking time.

- -A circuit arrangementfor operating this lamp is shown in-Fig. '2. In this circuit the lamp l is supplied ffrom the. electrical mains 1--1 through the impedance'il and the heater 4 which is connected in' series with the lamp." In operating thezlampthe; air stream required for cooling the seals is turned on and then the electrical supply to the lamp is switched on. The lamp then strikes and the lamp current which passes through the heater in series with the lamp heats it up and so evaporates the mercury rapidly,

thus causingthe lamp to.- approach its operating temperature 'pressnre quickly; When the lamp wattage has reached a certain value, the main cooling blast is turned on and at the same time the heater is short circuited. The lamp then continues to run-up to its. normal operating wattage which is determined by the-impedance in series with the lamp.

i In the event of a momentary "interruptioninthe mains supply, then the auxiliary air blast through the cooling jet 5 for condensing the mercury is turned on and the mercury is condensed very rapidly at the point in the bulb which is situated just above the heater 4.

ing' process, a relay 9 operated by thermostat I0 adjacent the lamp envelope" maybe arranged to deenerg-ize heater 4 and initiate operation'of mai-n' air blast I at any desiredlamp temperature, preferabl-y however at a temperature slightly below normal operatingtemperature:- -A relay t3 re sponsi-ve to the high voltage existing across the; lamp when it is out mayprevent 'thedeenergizing of air blast 2 and energization of heater 4 byrelay 9 un'ti-lthe-lamp-has restarted, after havingbeen deenergized 'while' Alternatively tothermostat W, a rel-ayconnected across the lamp and responsiveto a voltage slightly lower than normal operatingvoltage may operate-t0 deer;- ergize the heater and turn on themai n cooling blast as thelamp approaches operating temperatime during the starting process. Another relay I22, responsivetotl'iehigher voltage existing across the lamp when; it is out, may-beused -to start up the Tesla coil and to'turn on the auxiliary air blast forcooli-ng thel'amp rapid-1y in the event At the, same time the Tesla coil 6 is switched on and after a of an" interruptionin thepower supply. Whe'n the voltage across the lamp will then become very low. I

' Inorder to reduce the heating up time to a minimum it is necessary to supply hea t to the mercury as rapidly as possible. Thismay-be done by an external heater as described above, erby a heater which is actually enclosed within the lamp bulb itself; The gas used for starting in the lamp should g i-ve a. high cathode drop. inorder to produce a high wattage in the lamp bulb, buttiis gas: mus-t not be such that'a high starting voltagei's required The positionand size oi. the jet-used tor'the ai r tor coolinga spot on the bulb to condense the mercury should be adjust'edtc condense the mercury as rapidly as-possible, and also the position of thisj'et should be such that the m rcury is condensed-ma position on the'bulb in which itwiili receive heat. from the, auxiliary heater as quickly as possible. By this means. the time of'restrikingaand the heatin up time-willboth be reduced;

Another form oif lamp in which improveditimes for running up; and'for'restriking n'aaybe obtained is shown in Fig. 3. In this case the lamp I has on it an appendix M which contains the mercury. Around this appendix is placed a heater 4 which may be arranged to be in close contact with its surface, thus ensuring eflicient heat transference. Also this appendix may be cooled by an air jet 5 very e'fiicierttly, and by this the delay times for the lamp may be reduced even further.

It will generally be desirable to so shape and position the cooling and heating means of my into provide a minimum interference with the emitted light of the lamp. Thus, for example, when thelamp is used in combination with a parabolic: mirror for obtaining a light beam, it will be found advantageous to position the cooling or heating means or both directly between the rear of the lamp and the center of the mirror since light reflected from this portion usually returns to the lamp only to be intercepted by the lamp envelopeand is, therefore, already useless illumination purposes. Further the cooling pipesmay be -shapeci with flattened cylindrical or elliptical cross-section and so oriented that. minimum interference with the light results. Thus, where the lamp is positioned at theiocus of a parabolic reflector, the supply pipes carrying the cooling fluid may be positioned either vertically in front oi or'behinditheenvelope and may terminate ina nozzle having anaxis at right angles. .to. the. axisToi' tl ie' pipe... The nozzle may have an outwardly flared. orifice directed toward the lamp envelope." The vertical portion of the pipe may be of elliptical cross-.sectiontwi-th the major axis of the ellipse directed F's-long the axis of the beamso thatftline; ipipef'ohstructs as little as possible the effectice11ight. emission, It will beiunderstood rthattheheretn described arrangements are illustrative. of butzseueralforms electrical discharge device culnpzrising electrodes for sustaining; a discharge and energizing means therefor,.;'heating means; independent or said electrodes, to accelerate. thejapproachwof'said device to.v its normaloperating temperature, said heating means bei-ng energized upon starting. of the device, and: automaticrmeans ,for. deenergizsaidheatingmeans slamtly before said device reaches said normal operating; temperature andv for thereafter maintaining said heating means deenergized during; op rationqcfthe devrce.

2. In combinationwith a, high pressure vapor electrical discharge device comprising electrodes for sustaining a discharge and. energizing means therefor, cooling: means, heating, means, independent of said electrodes; :for accelerating. the approach of said discharge device to normal opera-tins temperature. said heating means being energized upon starting of the device, means for deenerg-izing said heating means shortly before said, device reaches normal operating temperature and for therealfter maintarining said heating means-deenergized during operation of the device, and means for initiating the operation of said cooling means onlywhen said device approaches normal operating temperature. and for continuing the operation ofi said cooling means being restarted at its normal operating temperature and pressure, and energizing means there for, heating means for accelerating the approach of said device to normal operating temperature, said heating means being energized upon starting of the device, cooling means, means I for deenergizing said heating means shortly before said device reaches its approximate normal operating temperature and for thereafter main tion obtains, and means for deenergizing said cooling means when said device drops to a temperature permitting reenergization of said device.

4. In combination with a high pressure vapor electrical discharge device which is incapable of being restarted at its normal operating temperature and pressure, and energizing means therefor, localized heating means for accelerating the approach of said device to normal operating temperature, said heating means being energized upon starting of the device localized, cooling means in close proximity to said heating means,

means for deenergizing said heating means shortly before said device reaches its approximate normal operating temperature and for thereafter maintaining said heating means deenergized during operation of the device, means for energizing said cooling means only upon deenergization of said device after normal operation obtains, and means for deenergizini; said cooling means when said device drops to a temperature permitting reenergization thereof, the

said cooling means being arranged to cool the same local portion of the device as is heated by said heating means.

5. In combination with a high pressure vapor said device after normal operation obtains and t for deenergizing said auxiliary cooling means when the temperature of saiddevice drops sufficiently to permit reenergization thereof, and means for deenergizing said primary cooling means until said device has reattained-approximate normal operating temperature.

6. In combination with a high pressure vapor electrical discharge device which is incapable of being restarted at its normal operating temperature and pressure, and energizing means therefor, localized heating means for accelerating the approach of said device to normal operating temperature, said heating means being energized upon starting of the device, primary cooling means and auxiliary localized cooling means in close proximity to said heating means, means for deenergizin-g said heating means shortly before said device reaches normal operating temperature and for initiating the operation of said primary cooling means thereafter throughout normal operation of the'device, means for initiating the operation of said auxiliary cooling means only upon deenergization of said device after normal operation obtains and for deenergizing said auxiliary cooling means when the temperature of said device drops sufficiently to permit reenergization thereof, and means for deenergizing said primary cooling means until said device has reattained approximate normal operating temperature, the said auxiliary cooling means being arranged to cool the same local portion of the device as is heated by said heating means.

7. In combination with a high pressure vapor electrical discharge device which is incapable of being restarted at its normal operating temperature and pressure, and energizing means therefor, heating means to accelerate the approach of said device to normal operating temperature,

said heating means being energized upon startingof the device, air blasts comprising a primary cooling means and an auxiliary cooling means in close proximity to said heating means, means for deenergizing said heating means shortly before said device reaches normal operating temperature and for initiating the operation of said primary cooling means thereafter throughout normal operation of the device, means for initiating the operation of said auxiliary cooling means only upon deenergization of said device after normal operation obtains and for deenergizing said auxiliary cooling means when the temperature of said device drops sufficiently to permit reenergization thereof, and means for deenergizing said primary cooling mean-s until said-device has reattained approximate normal operating temperature.

8. The method of accelerating the restarting of a high pressure vapor electrical discharge device upon deenergization thereof after normal operation obtains which comprises applying additional cooling means thereto in addition to the normal cooling means until the temperature of said device drops suificiently to permit reenergization thereof and thereafter discontinuing the normal cooling means until normal operation reobtains.

9. The method of operating a high pressure vapor electrical discharge device which comprises supplying electrical energy to the device to initiate a discharge therein, simultaneously applying localized heat thereto in addition to that supplied by the discharge until the device approaches its normal operating temperature, ap-

plying cooling means at a point in close proximity to the point of application of said heat when said device is deenergized after normal op 'eration obtains untilthe temperature of said device drops sufliciently to permit reenergization thereof. I

10. The method of operating a high pressure vapor electrical discharge device which comprises supplying electrical energy to the device to initiate a discharge therein, simultaneously applying heat thereto in addition to that supplied by the discharge until the device approaches its normal operating temperature and applying to said device when said device is deenergized after normal operation obtains cooling means in addition to the normal cooling means until the temperature of said device drops sufficien-tly to permit reenergization thereof.

- HARRY KEBBEIL BOURNE. 

